This invention relates to a thread trimmer provided in a pattern sewing machine for forming various patterns according to pattern data. The thread trimmer automatically cuts the specified portion of a crossover thread connecting a pattern and a next pattern to be formed.
In a known pattern sewing machine various patterns are formed according to various pattern data stored beforehand in a memory. The pattern sewing machine is provided with a thread trimmer comprising a fixed knife and a movable knife. At a desired time after a series of sewing operations, the thread trimmer trims needle thread and bobbin thread.
While the pattern sewing machine forms patterns on the fabric, a pattern is connected via a crossover thread to the next pattern to be formed. As shown in FIGS. 3A and 3B, when characters A and B are formed on the fabric, a stitch connecting the end a of the character A and the beginning b of the character B corresponds to the crossover thread. When the characters A and B are distant from each other, as shown in FIG. 3B, a needle bar is disconnected and no stitches are formed between the characters A and B. The needle thread connecting the end a of the character A and the beginning b of the character B also corresponds to the crossover thread. The crossover thread is formed during the operation of the pattern sewing machine. After the operation is completed, the crossover thread is no longer needed, so an operator cuts the crossover thread with scissors. The cutting of the crossover thread is both troublesome and time consuming.